Airflow control



Nov. 24, 1942. R w. OLSEN AIRFLOW CONTROL Filed April 29. 194

Inventor. Ronald \A/ Olsen,

y '3 His Attornqy.

Patented Nov. 24, W42

ICE

AIRFLOW ONTROL Ronald W. Olsen, Bloomfield, N. J., assignor to General Electric Company, a corporation of New York Application April 29, 1941, Serial No. 390,962

12 Claims.

My invention relates to fluid flow controls, and

although not limited thereto it has particular application to an arrangement for automatically controlling the flow of combustion air to a furnace,

In furnaces, and particularly in furnaces which are automatically fed with fuel, such as by a stoker, it is desirable to cut down off period burning when the fan is turned oil, and to allow the draft to build up gradually when the fan is turned on so as to allow a gradual pick up-of the fire and prevent blasting.

It is, therefore, an object of my invention to provide an improved arrangement for controlling the flow of a fluid.

A more specific object is to control the fluid flow by the cooperation of a'flow forcing means and a damper having a heated temperature responsive operator responsive to the cooling action of a by-passed fluid flow around the damper to effect the gradual opening of the damper upon operation of the fluid flow forcing means as well as the gradual closing of the damper when the operation of the flow forcing means is stopped.

Another object of my invention is to provide an improved arrangement for cutting down of! period burning of a furnace.

A further object of my invention is to provide an improved control arrangement for a stoker fired furnace for allowing a gradual increase in the flow of the forced air, upon the stoker blower being turned on in response to a call for heat.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out in the claims annexed to and forming a part of this specification.

The single flgurein the drawing illustrates an air flow control for a furnace which is provided with an embodiment of my invention.

In the arrangement illustrated in this drawing, I have provided an air flow control for a stoker fired furnace which includes a damper in a duct through which the combustion air passes, the

damper being movably operated by a thermal responsive device. This thermalresponsive device is mounted in heat conductive relationship with the furnace and is so connected to the damper as to substantially close it when the thermal responsive device is in a heated condition and to move the damper to a substantially wide open condition when the thermal responsive device thus allowing the damper to be gradually opened until it reaches a substantially ,wide open condition. In this manner off period burning of the furnace will be minimized when the fan and stoker are turned off and upon energization thereof the combustion air will be caused to flow into the furnace in a gradually increasing quantity so as to minimize blasting of the fire.

- Referring more particularly to the drawing, I have illustrated a furnace having a hearth i0 and which may be fed with fuel in any suitable manner, such as by a stoker, not shown. In order to provide air so that the coal will burn on the hearth iii, any suitable passage such as a duct II is provided which connects at one end with the hearth. In order to obtain a suitable draft, a fan i2 is provided which has its exhaust end l3 connected with an intake end I4 of the duct H. The fan may be operated in any suitable manner, such as by electric motor which is energized from a suitable source of electric potential through the conductors i5 and I6. Any suitable control device may be provided for controlling the electric motor which drives the fan, and in the'arrangement illustrated in the drawing, I have provided a thermostat I! for controlling a relay l8 which is connected in the line l5.

This thermostat may be responsive to any condition, such as the temperature of the room which is to be heated by the furnace, or to the temperature in the furnace, and when it closes.

its contacts the operating coil of the relay I8 is connected across the-auxiliary lines l9 and 20.

In order to control the airflow through the duct II I provide a damper 2| which is movably mounted therein in any suitable manner, such as by a shaft 22 which is pivotally mounted in the side walls of the duct. In order to 'control the movement of the damper I8 I provide a suitable thermal responsive device 23 which is operatively connected to the damper in any suitable manner, such as by a link 24 and a suitable leverage mechanism indicated generally by the numeral 25. The thermal responsive device 28 is mounted on a bracket 26 which is in turn supported by the furnace or hearth l0 so that the thermal responsive device is mounted in heat conductive relationship with the hearth. The thermal responsive device 23 is also mounted in any suitable manner so that the temperature thereof is effected by the passage of air which is forced by the fan l2 through the duct H. In the arrangement illustrated in the drawing, the temperature responsive device 23 is mounted in an auxiliary duct 27 which has an intake port 28 and an exhaust port 29 connected to the duct H.

Operation of my airflow control is as follows: When the thermostat l7 closes its contacts in response to a call for heat the electric motor which drives the fan l2 will be energized. This will force air through the auxiliary duct 2l ,the duct H being substantially closed at this time by the damper 2!. The thermal responsive device 23 is so connected to the damper through the link 24 and leverage mechanism 25 that when the device is allowed to be heated from the hearth i and through the bracket 26, it will cause the damper 2| to be moved to asubstantially closed position. This will prevent a natural draft through the duct H which causes off period burning, Therefore, when the air begins to flow through the auxiliary duct Tl the thermal responsive device 23 will' be cooled so that the damper 2| will begin tomove towards an open position. After a suitable time the thermal responsive device 23 will be sumciently cooled so the damper 2! will have moved to a substantially Wide open position. The amount of time necessary to allow this damper 2! to be moved to a wide open position may be varied by controlling the amount of air passing through the auxiliary duct 21, the amount of heat which will be conducted from the hearth through the bracket 26 to the thermal responsive device 23, and by the characteristics of the thermal responsive device itself. The amount of air passing through the duct 2? may be varied by providing a damper til at the intake. 28. By varying its position the amount of air available to cool the device: 23 may be controlled which will in turn control the time it takes the damper 20 to open and also the final open position. In this manner the maximum amount of air passing to the furnace may be controlled,

Instead of heating the thermal responsive device 23 by the heat from the furnace, any other suitable arrangement may be employed to accomplish this function such as providing a separate source of heat, such as an electric heating coil, as is employed in my fluid flow control described and claimed in my co-pending application Serial No. 390,963, filed concurrently herewith. and which is assigned to the same assignee.

as this present invention.

Although I have described my invention and its application as an airflow control for a sto'ker, it is to be understood that it has application for the control of the flow of any suitable liquid or any other suitable fluid.

Modifications of the particular arrangement which I have disclosed embodying my invention will occur to those skilled in the art, so that I do not desire my invention to be limited to the particular arrangement set forth and I intend in' the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An airflow control for a furnace including an air duct for conducting air to said furnace, a damper mounted therein for varying the area of the passage through which the air flows, a temperature responsive device, means including said device for moving said damper in response to variations in the temperature of said device, means for mounting said temperature responsive device in heat conductive relationship with said furnace, and means for conducting a portion of the air over said temperature responsive device so that it will be cooled thereby.

2. An airflow control for a furnace including an air duct for conducting air to said furnace, a damper mounted therein for varying the area of the passage through which the air flows, a temperature responsive device, means for mounting said temperature responsive device in heat conductive relationship with said furnace, means including said device for moving said damper so that the area of the passage is decreased as the temperature of said device is increased, means for producing a circulation of air through said duct to said furnace, and means for conducting air over said device to cool it upon said circulation means being energized in order to move said damper to increase the area of the passage.

3. An airflow control for a furnace including an air duct for conducting air to said furnace, a damper mounted therein for varying the area of the passage through which the air flows, a temperature responsive device, an auxiliary air duct having intake and outlet openings connected to said duct, said damper being mounted in said duct between said inlet and outlet openings, means for mounting said device in said auxiliary duct andin heat conductive relationship with said furnace, a fan for producing a flow of air through said duct to the furnace, and means including said device for moving said damper in response to variations in the temperature of said device so that when the fan is deenergized said damper will be substantially closed and when said fan is energized said device will becooled to move said damper to an open position.

4. A fluid flow control for controlling the flow of the fluids through a passage to a heating device including a damper movably mounted therein for varying the area of the passage through which the fluid flows, a temperature responsive device operatively connected to said damper for moving said damper in response to variations in the temperature of said device,- means for mounting said temperature responsive device in heat conductive relationship with said heating device, and means for conducting a portion of the fluid over said temperature responsive-device so that -it will be cooled thereby, and means for varying the amount of said portion of fluid which is conducted over said temperature responsive device. I

5. A fluid flow control including means for producing alflowcf fluid through a passage, a damper movably mounted in said passage for regulating the fluid flow therein, a temperature responsive device for moving said damper in response to variations in the temperature of said device, means for heating said device above the temperature of the fluid, and means for bypassing a portion of the fluid around said controlling the fluid flow therein, a temperature responsive device operatively connected to said damper, means for heating-said device above the temperature of the fluid to effect closure of said damper when said flow producing means is inactive, and means for supplying fluid to cool said temperature responsive device upon operation of said fluid flow producing means and thereby effeet a gradual opening of. said damper. 7. A fluid flow control including means operable for producing a flow of fluid through a passage, a damper mounted in said passage for restricting the fluid flow therein, a temperature responsive device, means for heating said device above the temperature of the fluid when said flow producing means is inactive, means includ-- ing said heated device for closing said damper and for opening said damper as the temperature of said device is decreased, and means for conducting fluid to eflect a gradual decrease in the temperature of said device upon operation of said fluid flow producing means.

8. In combination, a combustion heater, a forced draft fan for said heater having a damper for restricting the air flow therefrom and-provided with a heat responsive operating element responsive to the heat of combustion for closing said damper, and means for by-passing air around said damper to cool said operating element upon operation of said fan and thereby effect a gradual opening of said damper.

9. In combination, a combustion heater,a forced draft fan for said heater having a damper for restricting the air flow therefrom and provided with a heat responsive operating element responsive to the heat of combustion for closing said damper, means for by-passing air around said damper to cool said operating element upon operation of said fan and thereby effect a gradual opening of said damper, and adjustable control means for varying the amount of air bypassed around said damper to regulate the rate of cooling of said operating element.

10. In combination, a combustion furnace, a

forced draft fan having an outlet duct con- 7 nected with said furnace, a draft control damper mounted in said duct, an auxiliary duct for bypassing air around said damper, a heat responsive operating element mounted in said auxiliary duct in heat conducting relation with said furnace, operating connections between said element and said damper whereby said elementmoves said damper toward the closed position in response to heat from said furnace and toward the open position in response to the cooling action of the vby-passed air, and an adjustable control damper in said auxiliary duct for. regulating said cooling action.

11. In combination, means for forcing a flow of fluid through a passage, a damper movable in said passage for restricting fluid flow therein, a temperature responsive operating element for said damper, means for heating said operating element above the temperature of the fluid to close said damper when said fluid flow forcing means is inactive, and means for by-passing fluid around said damper to cool said element upon operation of said fluid flow forcing means and thereby effect a gradual opening of said damper.

12. In combination, means for forcing a flow of fluid through apassage, a damper movable in said passage for restricting fluid flow therein,

a temperature responsive operating element for said damper, means for heating said operating element above the temperature of the fluid to close said damper when said fluid flow forcing means is inactive, means including an auxiliary passage connected in parallel with said flrst passage for by-passing fluid around said damper to cool said element upon operation of said fluid flow forcing means and thereby eflect a gradual opening of said damper, and means adjustable in said auxiliary passage for varying the amount of fluid by-passed around said damper to regulate the rate of cooling of said operating element.

RONALD W. OLSEN.

CEQRTIFMATE OR CORRECTION;

Pate' t No. 2,505,155. 'N'oveniper 2 1;, 1912.

' 1201mm) w. 0mm.

it is hereby c ejrtified that erroh appears 'in the print t l-pacjlfication .of the above mimber'd p'gtent'r'equizzing corz etipni'as follows: Page .2, s eponq column, line 62, be gin ning with '5. A fluid flow" strikq out all Ito and including .the word'anq p'qriod-devide. in li ej'Tl -ccmpri sing claim 5'; and for't'h claim sfnow numbered "6", "7"; "'9"; "193', '11", and F13", read -"-6--',' --7--, --9- '-,.--1o--,.ana--11--,re ect1ve y, mam the eatin to the; pjlf-i nted specification; line"7, for '12 Claims regd --i1 Cla'izhs"; and that the said L etters'P atent Shbuld be r'ead with this correctioi therein the .1; the same mg f conf bmi to the reoord of the case inthe Patent office. v I r Signed and sealed this .2th day of Jamar y, A. D. 191+;

flgnry Van Arsdale, (seal) Acting commigg'io erflof Patents.- 

